Smart def injector for low temperature reductant delivery

ABSTRACT

A DEF injector is connected to the exhaust system of a vehicle upstream of an SCR catalyst, and is further connected to the ECU or DCU. An exhaust temperature sensor and an exhaust mass flow rate sensor are connected to the ECU or DCU, and further connected to the DEF injector. The ECU or DCU controls the DEF injector based on exhaust temperature and exhaust mass flow rate when the exhaust temperature is above a certain threshold. The DEF injector itself, or a dedicated DEF injector controller, overrides and/or supplements the control logic located within the ECU or DCU to control the DEF injector to inject DEF at reduced rates when the exhaust temperature and/or the exhaust mass flow rate are lower than the threshold for DEF injection set by the ECU or DCU.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional No. 62/859,372, filed Jun. 10, 2019, the entire contents of all of which are herein incorporated by reference.

BACKGROUND

This disclosure relates to a Smart DEF Injector for Low Temperature Reductant Delivery and its method of use. Particularly, this disclosure relates to an arrangement and method for calculating a maximum mass flow rate of DEF that may be injected for a sensed exhaust temperature and exhaust mass flow rate when the exhaust temperatures are below the normal temperature thresholds for DEF dosing.

RELATED ART

Diesel engines commonly operate with a lean air to fuel ratio, so that only part of the available oxygen is used in the fuel combustion reaction. While this helps to make diesel engines efficient, it also results in the formation of nitrogen oxides (NOx), an undesirable pollutant, during the combustion process. Presently, the Environmental Protection Agency (EPA) regulates the amount of NOx that may be emitted in vehicle exhaust, so that vehicle and engine manufacturers employ various techniques to reduce NOx emissions.

A common technique to reduce NOx tailpipe emissions involves the use of Selective Catalytic Reduction (SCR). SCR works by injecting a solution of urea, a reductant that is sometimes referred to as Diesel Exhaust Fluid (DEF), into the flow of vehicle engine exhaust, often referred to as “dosing.” Such DEF is commonly sold under the trademark AdBlue, or as ISO 22241 AUS325. The urea solution then evaporates and thermally decomposes due to the heat of the exhaust. Ammonia liberated from the urea then reacts with the NOx in the presence of a catalyst to form diatomic nitrogen (N2), water (H2O), and carbon dioxide (CO2). The catalyst is provided in the form of a structure, often a honeycomb shape or similar arrangement, with a coating such as a metal oxide or metal exchanged zeolites, located downstream in the exhaust flow from the location of urea injection. In order to maximize the effectiveness of the catalytic device, the evaporated urea and its thermal decomposition products, including the ammonia, must be properly mixed with the vehicle engine exhaust before entering the catalytic device. The SCR urea injector and catalytic device, together with a filter for removing particulates from the exhaust flow, generally located upstream in the exhaust flow from the SCR urea injector and catalytic device, are often collectively referred to as exhaust aftertreatment. DEF injection components are normally dependent on an external control module that may be an Engine Control Unit (ECU) or Diesel Control Unit (DCU), which control the quantity and timing of the DEF injection according to one or more algorithms.

Another technique to reduce NOx tailpipe emissions involves the use of Exhaust Gas Recirculation (EGR). EGR recirculates a percentage of exhaust gases back into the intake of the engine, in order to lower the amount of free oxygen in the intake air and to reduce the peak in-cylinder combustion temperatures. This, in turn, reduces the amount of NOx formation that takes place within the cylinders, while also reducing overall engine efficiency. Most modern diesel engines utilize both EGR and SCR, sometimes in combination with some form of combustion optimization. In order to control such factors as boost pressure, fuel injection timing and profile, EGR valve setting, and SCR injection, it is necessary to detect NOx emissions within the flow of exhaust, and to adjust the controls accordingly. Therefore, Engine Out Nitrogen Oxide (EONOx) sensors are often provided in order to detect the NOx emissions within the flow of exhaust and to provide this information by way of J1939 data bus to a controller such as the ECU or DCU.

In order to ensure complete evaporation and thermal decomposition of the urea solution, injection of DEF into the flow of the vehicle engine exhaust is normally limited to when the exhaust gas temperature and the catalytic device are above a minimum threshold temperature. Limiting injection of DEF into the flow of the vehicle engine exhaust to when the exhaust gas temperature and the catalytic device are above a minimum threshold temperature is further done to prevent the growth of urea or other deposits in the exhaust and aftertreatment system. Normally, DEF dosing is not initiated until the exhaust gas temperature and the catalytic device are above 190 degrees Celsius for standard DEF injectors, or 150 degrees Celsius for flash-boil DEF injectors.

As a result, SCR catalytic conversion of NOx does not occur below the aforementioned threshold temperatures, with the result that tailpipe emissions are higher under these conditions. Accordingly, there is an unmet need for an arrangement and method for reducing NOx and other greenhouse gas emissions under low exhaust temperature operating conditions.

SUMMARY

According to one embodiment of the Smart DEF Injector for Low Temperature Reductant Delivery, a vehicle has an engine, an ECU or DCU connected to the engine and configured to control the engine, an exhaust system connected to the engine, and an SCR catalyst connected to the exhaust system. A DEF injector is connected to the exhaust system upstream of the SCR catalyst, and further connected to the ECU or DCU. An exhaust temperature sensor is connected to the ECU or DCU, and further connected to the DEF injector. An exhaust mass flow rate sensor is connected to the ECU or DCU, and further connected to the DEF injector. The ECU or DCU is further configured with control logic for controlling the DEF injector based on exhaust temperature information provided by the exhaust temperature sensor and exhaust mass flow rate information provided by the exhaust mass flow rate sensor. The DEF injector is configured with control logic and is configured to override and/or supplement the control logic located within the ECU or DCU. The control logic of the DEF injector uses exhaust temperature information provided by the exhaust temperature sensor and exhaust mass flow rate information provided by the exhaust mass flow rate sensor to control the DEF injector to inject DEF at reduced rates when the exhaust temperature and/or the exhaust mass flow rate are lower than a threshold for DEF injection set by the ECU or DCU.

According to another embodiment of the Smart DEF Injector for Low Temperature Reductant Delivery, A Smart DEF Injection Arrangement is provided for a vehicle having an engine, an ECU or DCU connected to the engine and configured to control the engine, an exhaust system connected to the engine, and an SCR catalyst connected to the exhaust system. The Smart DEF Injection Arrangement includes a DEF injector connected to the exhaust system upstream of the SCR catalyst, and further connected to the ECU or DCU. An exhaust temperature sensor is connected to the ECU or DCU, and further connected to the DEF injector. An exhaust mass flow rate sensor connected to the ECU or DCU, and further connected to the DEF injector. The ECU or DCU is further configured with control logic for controlling the DEF injector based on exhaust temperature information provided by the exhaust temperature sensor and exhaust mass flow rate information provided by the exhaust mass flow rate sensor. The DEF injector is configured with control logic and is configured to override and/or supplement the control logic located within the ECU or DCU. The control logic of the DEF injector uses exhaust temperature information provided by the exhaust temperature sensor and exhaust mass flow rate information provided by the exhaust mass flow rate sensor to control the DEF injector to inject DEF at reduced rates when the exhaust temperature and/or the exhaust mass flow rate are lower than a threshold for DEF injection set by the ECU or DCU.

According to another embodiment of the Smart DEF Injector for Low Temperature Reductant Delivery, a method of reducing vehicle emissions in a vehicle having an engine includes several steps. The first step is connecting an ECU or DCU to the engine and configuring the ECU or DCU to control the engine. The second step is connecting an exhaust system to the engine. The third step is connecting an SCR catalyst to the exhaust system. The fourth step is connecting a DEF injector to the exhaust system upstream of the SCR catalyst, and further connecting the DEF injector to the ECU or DCU. The fifth step is connecting an exhaust temperature sensor to the ECU or DCU, and to the DEF injector. The sixth step is connecting an exhaust mass flow rate sensor to the ECU or DCU, and to the DEF injector. The seventh step is configuring the ECU or DCU with control logic for controlling the DEF injector based on exhaust temperature information provided by the exhaust temperature sensor and exhaust mass flow rate information provided by the exhaust mass flow rate sensor. The eighth step is configuring the DEF injector with control logic for overriding and/or supplementing the control logic configured within the ECU or DCU. The ninth step is controlling the DEF injector to inject DEF at reduced rates when the exhaust temperature and/or the exhaust mass flow rate are lower than a threshold for DEF injection set by the ECU or DCU, using the control logic of the DEF injector, exhaust temperature information provided by the exhaust temperature sensor, and exhaust mass flow rate information provided by the exhaust mass flow rate sensor.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a vehicle having an embodiment of a Smart DEF Injector for Low Temperature Reductant Delivery according to the present disclosure, as described herein;

FIG. 2 is a diagram of an embodiment of a Smart DEF Injector for Low Temperature Reductant Delivery and its method of use according to the present disclosure, as described herein; and

FIG. 3 is a graph of an exemplary DEF dosing rate as a percentage of fuel rate as a function of exhaust temperature for a given mass flow rate of exhaust according to an embodiment of a Smart DEF Injector for Low Temperature Reductant Delivery according to the present disclosure, as described herein.

DETAILED DESCRIPTION

Embodiments described herein relate to a Smart DEF Injector for Low Temperature Reductant Delivery, and to a method for the use thereof. Embodiments of the Smart DEF Injector for Low Temperature Reductant Delivery and its method of use may be applied to various types of passenger vehicles, recreational vehicles, and commercial vehicles, such as highway or semi-tractors with and without auxiliary power units (APUs), straight trucks with and without APUs, buses, fire trucks, agricultural vehicles, construction vehicles, campers, motorhomes, motorcycles, scooters, rail travelling vehicles, and trailers with APUs or refrigeration units. It is further contemplated that embodiments of the arrangement and method may be applied to vehicles having hybrid electric drive. It is further contemplated that, while presented herein as being used with diesel engines, embodiments of the arrangement and method may be applied to vehicles having engines configured for various fuels, such as, for non-limiting example, gasoline, diesel, propane, natural gas, and hydrogen, and particularly with respect to such engines being configured for lean-burn that use SCR.

Embodiments of the Smart DEF Injector for Low Temperature Reductant Delivery and its method of use utilize control logic that may be located partially or entirely within a DEF injector hardware itself, or in a dedicated DEF injector controller, rather than being located within the ECU or DCU. Alternately, embodiments of the Smart DEF Injector for Low Temperature Reductant Delivery and its method of use may continue to utilize control logic that is located within the ECU or DCU, but may override and/or supplement the control logic located within the ECU or DCU with its own control logic located partially or entirely within the DEF injector hardware itself, or in a dedicated DEF injector controller. Specifically, the DEF injector and/or its dedicated DEF injector controller uses sensed and/or calculated exhaust flow and temperature as inlet conditions to determine if DEF injection can be enabled at reduced rates at temperatures below the normal thresholds.

As noted previously, the normal temperature thresholds for DEF dosing are 190 degrees Celsius for standard DEF injectors and 150 degrees Celsius for flash-boil DEF injectors. Nevertheless, exhaust at temperatures below these thresholds are capable of evaporating and thermally decomposing urea at reduced rates without forming urea deposits, depending on exhaust temperatures, mass flow rates of exhaust, mass flow rate of fuel, and mass flow rates of DEF. Specifically, a non-dimensional number referred to as Excess Energy Ratio (EER) may be used to identify operating conditions that are unlikely to produce urea deposits. One method for calculating EER is according to the equation published in SAE 2015-01-0989, which is incorporated herein in its entirety. EER is calculated as the ratio of energy available in the exhaust to the energy required to evaporate water from an initial temperature of 70 degrees Celsius, as follows:

${EER} = {\frac{{\overset{.}{m}}_{exhaust} \times c_{pair} \times \left( {T_{exhaust} - 100} \right)}{{{\overset{.}{m}}_{DEF} \times c_{pwater} \times \left( {100 - 70} \right)} + {{\overset{.}{m}}_{DEF} \times h_{fgwater}}}.}$

-   -   Where:     -   m_(exhaust)=mass flow rate of exhaust     -   c_(pair)=heat capacity of exhaust     -   T_(exhaust)=exhaust temperature     -   m_(DEF)=mass flow rate of DEF     -   c_(pwater)=heat capacity of water     -   h_(fgwater)=heat of vaporization of water         If the EER is above a certain threshold, typically about 20, DEF         dosing at reduced rates is possible without resulting in urea         deposits. Therefore, an exemplary algorithm of the Smart DEF         Injector for Low Temperature Reductant Delivery and its method         of use sets the EER to a certain threshold, for non-limiting         example 20, and calculates a maximum mass flow rate of DEF that         may be injected for the sensed exhaust temperature and flow rate         when the exhaust temperatures are below the normal temperature         thresholds for DEF dosing of 190 degrees Celsius for standard         DEF injectors and/or 150 degrees Celsius for flash-boil DEF         injectors.

The Smart DEF Injector for Low Temperature Reductant Delivery and its method of use, therefore, provides a DEF injector that doses a reduced amount of DEF that does not result in deposit formation at reduced exhaust temperatures below the normal temperature thresholds for DEF dosing of 190 degrees Celsius for standard DEF injectors and/or 150 degrees Celsius for flash-boil DEF injectors, by calculating the amount of DEF dosing that may occur without exceeding the threshold EER. In order to do so, the Smart DEF Injector for Low Temperature Reductant Delivery and its method of use utilize input signals for exhaust flow and exhaust temperature. The reduced dosing may again occur independently of, or in addition to, any control algorithm located in the ECU or DCU, using logic contained within the DEF injector and/or in its dedicated DEF injector controller. Alternately, another embodiment of the Smart DEF Injector for Low Temperature Reductant Delivery and its method of use utilizes logic located within the ECU or DCU that is supplemental to the normal DEF dosing logic normally located therein.

Referring now to FIG. 1, a side view of a vehicle 10 having an embodiment of a Smart DEF Injector for Low Temperature Reductant Delivery and its method of use is shown. The vehicle 10 includes a chassis 12 having a frame 14, to which is attached a front axle 30 having front wheels 32, and a rear axle 40 having rear wheels 42. An engine 16 provides power for propulsion by way of a transmission (not shown) and a driveshaft (not shown), which is connected to the rear drive axle 40. The engine 16 may also be provided with an EGR system 18. The engine 16 may be controlled by an ECU or DCU 22, which may also be connected to other vehicle subsystems by way of a data bus 20, which may be embodied as a J1939 data bus.

The vehicle 10 of FIG. 1 is further provided with an exhaust system 50 which is connected to and receives exhaust from the engine 16, and which is provided with an exhaust aftertreatment system 52, in order to remove certain unwanted particulates and nitrogen oxides from the exhaust gases. In a non-limiting exemplary arrangement, the exhaust aftertreatment system 52 may include a Diesel Oxidation Catalyst (DOC) 56, a Diesel Particulate Filter (DPF) 58, a Smart DEF Injector for Low Temperature Reductant Delivery 60, and an SCR catalyst 62. In the embodiment of the Smart DEF Injector for Low Temperature Reductant Delivery and its method of use shown in FIG. 1, an EONOx sensor 54, an exhaust temperature sensor 64, and an exhaust flow sensor 66 are situated at the upstream end of the exhaust aftertreatment system 52, and are connected to the ECU or DCU 22 by way of the data bus 20. It is also contemplated that the exhaust temperature sensor 64 and/or the exhaust flow sensor 66 may be located downstream of the DOC 56 and DPF 58, just upstream of the Smart DEF Injector for Low Temperature Reductant Delivery 60 and the SCR catalyst 62. It is further contemplated that the Smart DEF Injector for Low Temperature Reductant Delivery 60 and the SCR catalyst 62 may be located upstream of the DOC 56 and DPF 58. In this way, the EONOx sensor 54, the exhaust temperature sensor 64, and the exhaust flow sensor 66 provide information concerning the nitrogen oxide content of the exhaust flow, the temperature of the exhaust flow, and the rate of flow of the exhaust in the way of sensor signals to the ECU or DCU 22 via the data bus 20. The ECU or DCU 22 uses the information concerning the nitrogen oxide content of the exhaust flow, the temperature of the exhaust flow, and the rate of flow of the exhaust to control, for non-limiting example, operating parameters of the engine 16, the EGR system 18, and the Smart DEF Injector for Low Temperature Reductant Delivery 60.

Turning now to FIG. 2, a graphic representation is shown of an exhaust system 50 having an exhaust aftertreatment system 52 and implementing an embodiment of the Smart DEF Injector for Low Temperature Reductant Delivery 60. The exhaust aftertreatment system 52 again includes a DOC catalyst 56, a DPF 58, and an SCR catalyst 62. It is noted that FIG. 2 shows the DOC catalyst 56 and DPF 58 upstream of the Smart DEF Injector for Low Temperature Reductant Delivery 60 and the SCR catalyst 62. However, it is also contemplated that the Smart DEF Injector for Low Temperature Reductant Delivery 60 and the SCR catalyst 62 may be located upstream of the DOC catalyst 56 and DPF 58. In any case, an EONOx sensor 54 (not shown) may be provided upstream of the DOC catalyst 56 and DPF 58. The Smart DEF Injector for Low Temperature Reductant Delivery 60 is located upstream of the SCR catalyst 62, and is used to dose DEF from a DEF tank 70 into the flow of exhaust prior to the SCR catalyst 62, so that the DEF urea solution evaporates and thermally decomposes due to the heat of the exhaust. As noted previously, ammonia liberated from the urea then reacts with the NOx in the presence of the SCR catalyst 62 to form diatomic nitrogen (N2), water (H2O), and carbon dioxide (CO2).

The exhaust temperature sensor 64 and the exhaust flow sensor 66 provide information concerning the temperature of the exhaust flow and the rate of flow of the exhaust in the way of sensor signals to the ECU or DCU 22. The ECU or DCU 22 uses the information concerning the temperature of the exhaust flow and the rate of flow of the exhaust to control the Smart DEF Injector for Low Temperature Reductant Delivery 60 when the temperature of the exhaust is above 190 degrees Celsius for a Smart DEF Injector for Low Temperature Reductant Delivery 60 embodied as a standard DEF injector, or when the temperature of the exhaust is above 150 degrees Celsius for a Smart DEF Injector for Low Temperature Reductant Delivery 60 embodied as a flash-boil DEF injector. The exhaust temperature sensor 64 and the exhaust flow sensor 66 also provide information concerning the temperature of the exhaust flow and the rate of flow of the exhaust in the way of sensor signals to the Smart DEF Injector for Low Temperature Reductant Delivery 60 itself. The Smart DEF Injector for Low Temperature Reductant Delivery 60 uses the information concerning the temperature of the exhaust flow and the rate of flow of the exhaust to take over and control DEF dosing at reduced rates when the temperature of the exhaust is below 190 degrees Celsius for a Smart DEF Injector for Low Temperature Reductant Delivery 60 embodied as a standard DEF injector, or when the temperature of the exhaust is below 150 degrees Celsius for a Smart DEF Injector for Low Temperature Reductant Delivery 60 embodied as a flash-boil DEF injector.

Alternately, the exhaust temperature sensor 64 and the exhaust flow sensor 66 may provide information concerning the temperature of the exhaust flow and the rate of flow of the exhaust in the way of sensor signals to a dedicated Smart DEF Injector controller 68, which may be connected between the ECU or DCU 22 and the Smart DEF Injector for Low Temperature Reductant Delivery 60, or may be connected independently to the Smart DEF Injector for Low Temperature Reductant Delivery 60 without being interposed between the ECU or DCU 22 and the Smart DEF Injector for Low Temperature Reductant Delivery 60. In either case, the dedicated Smart DEF Injector controller 68 uses the information concerning the temperature of the exhaust flow and the rate of flow of the exhaust to take over and control DEF dosing at reduced rates when the temperature of the exhaust is below 190 degrees Celsius for a Smart DEF Injector for Low Temperature Reductant Delivery 60 embodied as a standard DEF injector, or when the temperature of the exhaust is below 150 degrees Celsius for a Smart DEF Injector for Low Temperature Reductant Delivery 60 embodied as a flash-boil DEF injector, similar to the embodiment of the Smart DEF Injector for Low Temperature Reductant Delivery 60 wherein such control is exercised by the Smart DEF Injector for Low Temperature Reductant Delivery 60 itself.

FIG. 3 shows a DEF dosing rate graph 100 that gives an exemplary DEF dosing rate 102 as a percentage of fuel rate as a function of exhaust temperature 104 for a given mass flow rate of exhaust. The exemplary DEF dosing rate graph 100 is presented for illustration purposes, and may not represent actual DEF dosing rates. What is illustrated by FIG. 3, however, is that when the temperature of the exhaust is above 190 degrees Celsius for a Smart DEF Injector for Low Temperature Reductant Delivery 60 (not shown) embodied as a standard DEF injector, the ECU or DCU 22 controls the Smart DEF Injector for Low Temperature Reductant Delivery 60 according to an ECU/DCU controlled standard type Smart DEF Injection function or algorithm 106. When the temperature of the exhaust is below 190 degrees Celsius for a Smart DEF Injector for Low Temperature Reductant Delivery 60 (not shown) embodied as a standard DEF injector, the Smart DEF Injector for Low Temperature Reductant Delivery 60 itself, or in an alternate embodiment the dedicated Smart DEF Injector controller 68, controls the Smart DEF Injector for Low Temperature Reductant Delivery 60 according to a Smart DEF Injector or dedicated Smart DEF Injector controller controlled standard type Smart DEF Injection function or algorithm 110.

When the temperature of the exhaust is above 150 degrees Celsius for a Smart DEF Injector for Low Temperature Reductant Delivery 60 (not shown) embodied as a flash-boil type DEF injector, the ECU or DCU 22 controls the Smart DEF Injector for Low Temperature Reductant Delivery 60 according to an ECU/DCU controlled flash-boil type Smart DEF Injection function or algorithm 108. When the temperature of the exhaust is below 150 degrees Celsius for a Smart DEF Injector for Low Temperature Reductant Delivery 60 (not shown) embodied as a flash-boil type DEF injector, the Smart DEF Injector for Low Temperature Reductant Delivery 60 itself, or in an alternate embodiment the dedicated Smart DEF Injector controller 68, controls the Smart DEF Injector for Low Temperature Reductant Delivery 60 according to a Smart DEF Injector or dedicated Smart DEF Injector controller controlled flash-boil type Smart DEF Injection function or algorithm 112.

In this way, the Smart DEF Injector for Low Temperature Reductant Delivery and its method of use is able to lower unwanted exhaust NOx emissions in a region of exhaust temperature and exhaust mass flow rate below the capability of normal DEF injector control systems. Further, the Smart DEF Injector for Low Temperature Reductant Delivery and its method of use is able to accomplish this without altering the programming of normal ECU/DCU controlled DEF injection, which allows the Smart DEF Injector for Low Temperature Reductant Delivery and its method of use to be implemented on existing vehicles without extensive modification. That being said, the Smart DEF Injector for Low Temperature Reductant Delivery and its method of use may further be able to enable higher Engine-Out (EO) NOx levels, so that engines may be designed to operate at greater fuel economy, while still lowering overall tailpipe emissions. Conversely, the Smart DEF Injector for Low Temperature Reductant Delivery and its method of use may be able to enable ultra-low tailpipe NOx levels and meet tailpipe NOx and greenhouse gas (GHG) requirements for low load cycles (LLC), which may be included in future regulatory rulings.

While the Smart DEF Injector for Low Temperature Reductant Delivery and its method of use has been described with respect to at least one embodiment, the arrangement and method can be further modified within the spirit and scope of this disclosure, as demonstrated previously. This application is therefore intended to cover any variations, uses, or adaptations of the system and method using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which the disclosure pertains and which fall within the limits of the appended claims. 

What is claimed is:
 1. A vehicle having a Smart DEF Injector for Low Temperature Reductant Delivery, comprising: an engine; an Engine Control Unit (ECU) or Diesel Control Unit (DCU) connected to the engine and configured to control the engine; an exhaust system connected to the engine; an SCR catalyst connected to the exhaust system; a Diesel Exhaust Fluid (DEF) injector connected to the exhaust system upstream of the SCR catalyst, and further connected to the ECU or DCU; an exhaust temperature sensor connected to the ECU or DCU, and further connected to the DEF injector; an exhaust mass flow rate sensor connected to the ECU or DCU, and further connected to the DEF injector; wherein: the ECU or DCU is further configured with control logic for controlling the DEF injector based on exhaust temperature information provided by the exhaust temperature sensor and exhaust mass flow rate information provided by the exhaust mass flow rate sensor; the DEF injector is configured with control logic and is configured to override and/or supplement the control logic located within the ECU or DCU; the control logic of the DEF injector uses exhaust temperature information provided by the exhaust temperature sensor and exhaust mass flow rate information provided by the exhaust mass flow rate sensor to control the DEF injector to inject DEF at reduced rates when the exhaust temperature and/or the exhaust mass flow rate are lower than a threshold for DEF injection set by the ECU or DCU.
 2. The vehicle of claim 1, further comprising: a dedicated DEF injector controller connected to the DEF injector, wherein: the exhaust temperature sensor is further connected to the DEF injector by way of the dedicated DEF injector controller; the exhaust mass flow rate sensor is further connected to the DEF injector by way of the dedicated DEF injector controller; and the control logic of the DEF injector resides within the dedicated DEF injector controller.
 3. The vehicle of claim 2, wherein: the dedicated DEF injector controller is further connected to the ECU or DCU.
 4. The vehicle of claim 1, wherein: the control logic of the DEF injector controls the DEF injector to inject DEF at reduced rates determined by setting an Excess Energy Ratio (EER) to a threshold value and solving for a mass flow rate of DEF.
 5. The vehicle of claim 4, wherein: the mass flow rate of DEF being determined as a percentage of fuel mass flow rate.
 6. The vehicle of claim 1, wherein: the DEF injector is a standard type DEF injector; and the threshold for DEF injection set by the ECU or DCU is 190 degrees Celsius.
 7. The vehicle of claim 1, wherein: the DEF injector is a flash-boil type DEF injector; and the threshold for DEF injection set by the ECU or DCU is 150 degrees Celsius.
 8. A Smart DEF Injection Arrangement for Low Temperature Reductant Delivery for a vehicle having an engine, an Engine Control Unit (ECU) or Diesel Control Unit (DCU) connected to the engine and configured to control the engine, an exhaust system connected to the engine, and an SCR catalyst connected to the exhaust system, comprising: a Diesel Exhaust Fluid (DEF) injector connected to the exhaust system upstream of the SCR catalyst, and further connected to the ECU or DCU; an exhaust temperature sensor connected to the ECU or DCU, and further connected to the DEF injector; an exhaust mass flow rate sensor connected to the ECU or DCU, and further connected to the DEF injector; wherein: the ECU or DCU is further configured with control logic for controlling the DEF injector based on exhaust temperature information provided by the exhaust temperature sensor and exhaust mass flow rate information provided by the exhaust mass flow rate sensor; the DEF injector is configured with control logic and is configured to override and/or supplement the control logic located within the ECU or DCU; the control logic of the DEF injector uses exhaust temperature information provided by the exhaust temperature sensor and exhaust mass flow rate information provided by the exhaust mass flow rate sensor to control the DEF injector to inject DEF at reduced rates when the exhaust temperature and/or the exhaust mass flow rate are lower than a threshold for DEF injection set by the ECU or DCU.
 9. The arrangement of claim 8, further comprising: a dedicated DEF injector controller connected to the DEF injector, wherein: the exhaust temperature sensor is further connected to the DEF injector by way of the dedicated DEF injector controller; the exhaust mass flow rate sensor is further connected to the DEF injector by way of the dedicated DEF injector controller; and the control logic of the DEF injector resides within the dedicated DEF injector controller.
 10. The arrangement of claim 9, wherein: the dedicated DEF injector controller is further connected to the ECU or DCU.
 11. The arrangement of claim 8, wherein: the control logic of the DEF injector controls the DEF injector to inject DEF at reduced rates determined by setting an Excess Energy Ratio (EER) to a threshold value and solving for a mass flow rate of DEF.
 12. The arrangement of claim 11, wherein: the mass flow rate of DEF being determined as a percentage of fuel mass flow rate.
 13. The arrangement of claim 8, wherein: the DEF injector is a standard type DEF injector; and the threshold for DEF injection set by the ECU or DCU is 190 degrees Celsius.
 14. The arrangement of claim 8, wherein: the DEF injector is a flash-boil type DEF injector; and the threshold for DEF injection set by the ECU or DCU is 150 degrees Celsius.
 15. A method of reducing vehicle emissions in a vehicle having an engine, comprising the steps of: connecting an Engine Control Unit (ECU) or Diesel Control Unit (DCU) to the engine and configuring the ECU or DCU to control the engine; connecting an exhaust system to the engine; connecting an SCR catalyst to the exhaust system; connecting a Diesel Exhaust Fluid (DEF) injector to the exhaust system upstream of the SCR catalyst, and further connecting the DEF injector to the ECU or DCU; connecting an exhaust temperature sensor to the ECU or DCU, and to the DEF injector; connecting an exhaust mass flow rate sensor to the ECU or DCU, and to the DEF injector; configuring the ECU or DCU with control logic for controlling the DEF injector based on exhaust temperature information provided by the exhaust temperature sensor and exhaust mass flow rate information provided by the exhaust mass flow rate sensor; configuring the DEF injector with control logic for overriding and/or supplementing the control logic configured within the ECU or DCU; controlling the DEF injector to inject DEF at reduced rates when the exhaust temperature and/or the exhaust mass flow rate are lower than a threshold for DEF injection set by the ECU or DCU, using the control logic of the DEF injector, exhaust temperature information provided by the exhaust temperature sensor, and exhaust mass flow rate information provided by the exhaust mass flow rate sensor
 16. The method of claim 15, further comprising the steps of: connecting a dedicated DEF injector controller to the DEF injector; further connecting the exhaust temperature sensor to the DEF injector by way of the dedicated DEF injector controller; further connecting the exhaust mass flow rate sensor to the DEF injector by way of the dedicated DEF injector controller; and configuring the control logic of the DEF injector within the dedicated DEF injector controller.
 17. The method of claim 16, further comprising the steps of: further connecting the dedicated DEF injector controller to the ECU or DCU.
 18. The method of claim 15, further comprising the steps of: controlling the DEF injector to inject DEF at reduced rates determined by setting an Excess Energy Ratio (EER) to a threshold value and solving for a mass flow rate of DEF using the control logic of the DEF injector.
 19. The method of claim 15, wherein: the DEF injector is a standard type DEF injector; and the threshold for DEF injection set by the ECU or DCU is 190 degrees Celsius.
 20. The method of claim 15, wherein: the DEF injector is a flash-boil type DEF injector; and the threshold for DEF injection set by the ECU or DCU is 150 degrees Celsius. 